Experimental studies: Radiation effect on the testis will be studied by administering doses varying from 100 - 5,000 rads. Changes in the germinal cells, in the supporting cells, in the connective tissue and in blood vessels will be examined. Studies of radiation nephritis will be continued by administering moderate doses (1,500 - 2,000 rads) to an exteriorized kidney. Mesothelioma induced in hamsters by intrapleural administration of asbestos will be studied by light and electron microscopy and histochemically for the presence of acid mucopolysaccharides. Human renal diseases: Detailed morphological studies including electron microscopy and immunofluorescence microscopy will be conducted on renal biopsies and autopsy tissues and correlated with clinical and physiological changes. The following disease entities will be included: mesangio-capillary glomerulonephritis, primary and secondary amyloidosis, diabetes mellitus, toxic nephropathy and systemic lupus erythematosus. Structure of human mesothelioma, both peritoneal and pleural, will be examined by light and electron microscopy and by histochemical techniques and correlated with the clinical course and the outcome. Bibliographic references: Grishman, E. and Churg, J. Focal Glomerular Sclerosis in Nephrotic Patients: An Electron Microscopic Study of Glomerular Podocytes. Kidney International 7:111-122, 1975; Churg, J. Peritoneal Mesothelioma. Environ. Health Perspectives 9:317- 318, 1974.